1. Field of the Invention
The present invention relates to a method for manufacturing electrodes of a plasma display panel (hereafter referred as PDP), and more particularly, to a method for manufacturing electrodes for preventing electrodes from experiencing edge curl effects and for increasing the quality of the PDP.
2. Description of the Prior Art
Recently, the field of multimedia applications is developing quickly. Users have a great demand for entertainment equipment. Conventionally, the cathode ray tube (CRT) display is commonly used. However, the cathode ray tube display does not meet the needs of multimedia technology because of it has a large volume. Therefore, many flat panel display technologies such as liquid crystal display (LCD), PDP, and field emission display (FED) have been developed. These display technologies are capable of manufacturing a thin, light, short and small monitor, and thus these technologies are going to be the mainstream technology for the future. Among these technologies, the PDP is attracting attention in the field of displays as a full-color display apparatus having a large size display area and is especially popular for use as a large size television or an outdoor display panel. This is because of its capability of serving as a high quality display resulting from the fact that it is a self-light emitting type display, has a wide angle of visibility, and has a short response time. Furthermore, the dimensions of the PDP can easily be increased in scale due to its simplicity in the manufacturing process.
A color PDP is a display in which ultraviolet rays are produced by gas discharge to excite phosphors so that visible lights are emitted therefrom to perform a display operation. Generally, a 3-electrode type PDP including a common electrode, a scan electrode and an address electrode is employed in the AC type PDP.
In a conventional 3-electrode AC type PDP, the address electrodes are disposed between parallel barrier ribs on a rear substrate. A plurality pair of conductive electrodes are arranged in parallel, and each pair of the conductive electrodes, including the common electrode and the scan electrode, is disposed in a direction perpendicular to the address electrodes and barrier ribs, thereby a plurality of ruminant cells are scaled therein.
The common and scan electrodes generally include a transparent electrode and a bus electrode. The transparent electrode is formed by the material indium tin oxide (ITO) (e.g., a mixture of In2O3 and SnO2). The conductivity of the transparent electrode is low in comparison with that of metal and therefore a narrow width and fine conductive layer is added as the bus electrode on the transparent electrode to enhance its conductivity. The gap between the common electrode and scan electrode is set to obtain preferred fire voltage. A sustaining voltage is applied to the common electrode and the scan electrode to drive the PDP.
According to the above description, we know that electrodes are key units of a PDP and thus the method for manufacturing electrodes is very important. Please refer to FIG. 1 to FIG. 3. FIG. 1 to FIG. 3 are schematic diagrams for illustrating a method for manufacturing electrodes of a PDP according to the prior art. As shown in FIG. 1, a front substrate 10, for example, glass or other transparent boards, is provided. Transparent electrodes 12 and 14 formed by the material of ITO are disposed on the front substrate 10 and a discharge gap 16 is present between the transparent electrodes 12 and 14. A black photosensitive paste film 18 of negative-working type and a main photosensitive conductive paste film 20 of negative-working type cover the front substrate 10, the transparent electrode 12, and the transparent electrode 14. Then, utilizing a photo mask 22, an exposure process is performed. The photo mask 22 includes a shade region 24 and an opening region 26. In the exposure process, light 27, for example, a collimated ultraviolet (UV) light passes through the opening region 26 and is blocked by the shade region 24.
As shown in FIG. 2, after the exposure process, a development process is performed for patterning the black photosensitive paste film 18 and the main photosensitive conductive paste film 20. Because the black photosensitive paste film 18 and the main photosensitive conductive paste film 20 are negative-working type, areas covered by the shade region 24 are removed to form bus electrodes 28 and 30. Since the exposure of the bottom region of the bus electrodes 28 and 30 is less than the exposure of the top region of the bus electrodes 28 and 30, especially in the edges of the bus electrodes 28 and 30, the bus electrodes 28 and 30 look like trapezoids, in which an upper side is wider than a lower side.
As shown in FIG. 3, a firing process is performed. A tensile force occurs while high temperature firing and causes the edges of the bus electrodes 28 and 30 to not adhere to the transparent electrodes 12 and 14 well. Therefore, edge curls 32, 34, 36, and 38 of the bus electrodes 28 and 30 occur.
In the prior art, the height of the edge curls 32, 34, 36, and 38 is approximately 1-10 microns and the thickness of the buses 28 and 30 is approximately 2-20 microns. A dielectric layer cannot easily be formed under the edge curls 32, 34, 36, and 38 and air bubbles will be formed, causing breakdown around the edge curls 32, 34, 36, and 38. This will seriously influence the quality of the PDP. There are two methods for improving the edge curls 32, 34, 36, and 38: decreasing the thickness of the bus electrodes 28 and 30 and changing the component of the black photosensitive paste film 18 and the main photosensitive conductive paste film 20 to increase the adhesion ability between the bus electrodes 28 and 30 and the transparent electrodes 12 and 14. However, the two methods both will influence the resistance of the electrodes.